The SN76477N

[fearlesstorch]

I know I could try to yank one out of my speak and read, but that would be a waste of a good speak.  I found a schematic that used one, and I wanted to try it because it's cool.  They just happen to be very difficult to find.  Does anyone know where I could find one or at least a suitable replacement?  I also have the data sheet and the schematic if anyone wants to see them.

[expanoncolin]

Here's a datasheet for whoever else is curious:
http://www.engr.colostate.edu/~jpowell/sn76477.pdf

I think they're almost impossible to find... what's the schematic you're looking at?

-Colin

[expanoncolin]

P.S. - This guy has 2 of them for sale.

http://www.decodesystems.com/old-ics.html

-Colin

[fearlesstorch]

id put it up, but i cant seem to find it.  if you want i can email the scan of it to you.  its just a sounds effects generator from an old forrest m mims III book.  its a very simple circuit that really doesnt do anything except put the IC to use.  i really want to expand upon it as much as i can, perhaps with a few well placed lfo's or something.  it seems pretty open-ended and easily modified.  

thanks a lot for the hookup.[/img]

[expanoncolin]

That IC is pretty funny... It was basically the atari's soud system in one little box.  Great stuff...  It could certainly be mangled into a nice random noisemaker.

-Colin

[fearlesstorch]

but is it worth the 15 or 20 bucks to buy the chip?  im really interested in exploring it, but is it worth the money?  thats the bottom line, im cheap.

[expanoncolin]

but is it worth the 15 or 20 bucks to buy the chip?  im really interested in exploring it, but is it worth the money?  thats the bottom line, im cheap.

Naw, you can do the same things with an OA VCO with a quad op amp or two.

-Colin

[sidandnancy]

This site has some articles from old magazines about this cool chip:
http://www.mkv.mh.se/personal/per/diy/76477/

This guy built one of those projects:
http://www.retrosonik.com/KlangeMain.htm

And Rude 66's "Toy":
http://members.ams.chello.nl/rlekx/sn76477.htm

The beauty of the chip is how simple it is to use. A few caps, switches, resistors, and pots- viola - wet your pants noise!

You won't find one in your speak and spell, but those have their own fun sounds.

[hyperenough]

Speak & spells or any other item that I know off hand doesn't use the SN76477 chip except for the Synare Electric Drums

Here's an example
http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... eName=WDVW

There are two chips out there you can look for. The SN76477 and the SN76477N one is a smaller dip size than the other.

TI also had another chip which was it's little brother called the SN94281.

You could use the chip inside the speak but you'd have to build a processor to control the phonemes that are stored on the chip. That's a lot of work unless you have a Z80 lying around. Saw an article where it depicted how to write the program to interface with the chip and make noises with it.

[expanoncolin]

TI also had another chip which was it's little brother called the SN94281.

What's the technical difference here?

[hyperenough]

God, I can't recall at the moment off the top of my head. Thomas Henry has a great compilation of his articles and in that he discusses the difference.  It's considerably more rare than the SN76477 chip too.

[sidandnancy]

The SN94281 (and the identical SN76495) have less features the the big brothers. No decay controls, and no oscillator input. I don't see a "one shot" pin either. The Henry aritcle has a couple cheats to extract the noise, lfo, and vco independantly.

The SN76488 is another big boy with all the features of the 77, plus it had a straigt audio amp to drive a speaker.

There is probably a Radio Shack somewhere with a back room full of unsold stock. There were just not that many guys who wanted to build whistle sounds for their model trains.

[expanoncolin]

Interesting.  Sounds like a fun chip...  Although I'd feel like I was cheating, just using 1 chip instead of making a full-fledged synth-y thing.

-Colin

[sidandnancy]

This toy uses the SN76488

http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 55435&rd=1

If you see one at the Goodwill grab it.


Then sell it on ebay!

[expanoncolin]

This toy uses the SN76488

http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 55435&rd=1

If you see one at the Goodwill grab it.


Then sell it on ebay!

That thing looks awesome.  I'd love to see some little kid plying with it.

-Colin